Hussein was the grandson of the Prophet Mohammed. After Mohammed’s death in 632, Hussein was killed during a battle near Karbala for control of the Muslim nation.

Hussein’s 7th-century death led to a split between Sunni and Shi’ite Muslims that still divides the sects today.

During former Iraqi President Saddam Hussein’s rule, the Sunni leader forbade Shi’ite pilgrims from making the journey on foot. But after the US-led invasion toppled the President, the pilgrimages grew in numbers.

In recent years, scores of pilgrims have been killed in attacks blamed on Sunni extremists. Despite ongoing dangers, Shi’ite pilgrims still make the journey to Karbala.